Spark discharge arrangement



Jan. 24, 1967 F. FRUNGEL ET SPARK DISCHARGE ARRANGEMENT 3 Sheets-Sheet 1 Filed Dec. 9, 1963 Jan. 24, 1967 F. FRUNGEL ET AL 3,300,682

SPARK DISCHARGE ARRANGEMENT Filed Dec. 9, 1963 3 Sheets-Sheet 2 GENE/6470,?

Q) LL n INVENTOR United States Patent 3,300,682 SPARK DISCHARGE ARRANGEMENT Frank Friingel, Hamburg-Rissen, and Gert Riider, Hamburg-Lokstedt, Germany, assignors to Impulsphysik Dr.- Ing. Frank Friingel G.m.b.H., Hamburg-Rissen, Germany Filed Dec. 9, 1963, Ser. No. 328,959 Claims priority, application Germany, Dec. 10, 1962, J 22,805 11 Claims. (Cl. 315171) The present invention concerns spark discharge arrangements and more specifically deals with the problems involved in suitably igniting a spark gap device.

The task of igniting a spark gap i.e. initiating a sparkover between the electrodes of a spark gap, involves the problem of igniting the spark gap at a predetermined exact moment no matter whether the particular spark gap serves itself as a switching or control element or whether it serves for emitting light impulses. For igniting a spark gap of this type conventionally a third electrode or even a plurality of such electrodes has been used which is or are arranged around the main spark electrodes or between the latter or both. According to the conventional method an igniting impulse potential is established between those auxiliary electrodes and the main electrodes whereby a previously charged storage capacitor is discharged across the electrodes provided that the igniting impulse potential is capable of wholly or partly bridging or ionizing the spaces or the space between the two main spark electrodes so that now the main discharge or spark-over can take place.

However, this conventional arrangement entails the disadvantage that the igniting electrodes must be carefully adjusted whereby discharge light sources or spark gap systems of this type are rendered structurally complicated and expensive. In addition, another disadvantage exists which is due to the fact that the amount of light generated by a spark is the greater, the greater is, at a given potential and capacity of a discharge capacitor, the distance between the spark electrodes and the number of ionized atoms. Such a desirable greater light emission would be obtainable by increasing the distance between the spark electrodes and by increasing the gas pressure in the areas of these electrodes. However, by doing this automatically the required igniting potential is increased. Therefore, the conventional spark gap devices are not suited for satisfactorily causing a spark-over under the above-mentioned conditions. For instance, if at a given spacing between the spark gap electrodes the break-down voltage of the particular spark gap amounts to kv., then it is generally only possible to reduce this voltage to about 7 kv. by selecting special igniting electrodes and igniting sparks. However, the correct adjustment and selection of voltage, electrode spacing and gas pressure is under these circumstances very critical so that one cannot rely on a proper ignition effect. On the other hand, if it were possible to reduce further the igniting voltage while leaving gas pressure and electrode spacing unchanged, then the efliciency of the spark namely the ratio between light emission and consumed electrical energy would greatly increase.

In view of this state of the art it is one object of this invention to provide for an arrangement by which a spark gap can be ignited without the necessity of using auxiliary igniting electrodes and in such a manner that at the same time the efficiency of the light emission and the reliability of the igniting procedure is increased.

It is a further object of this invention to provide for an arrangement of the type set forth which is in itself compartively simple and entirely reliable in operation.

With the above objects in view the invention includes a spark discharge arrangement comprising, in combination,

ice

spark gap means having two spaced spark electrodes; a source of electric energy; circuit means having at least a portion of low inductance and connecting said spark gap means with said source of electric energy; storage capacitor means connected in parallel with said spark gap means, said storage capacitor means being chargeable by said source to a predetermined potential and dischargeable across said spark gap means when a sufiicient predetermined conductivity is established between said two electrodes; spark discharge initiator means capable of applying to said spark gap means a steeply rising igniting impulse causing a spark-over between said electrodes so as to produce thereby said predetermined conductivity therebetween; and inductive reactance means surrounding at least a portion of said low inductance portion ofsaid circuit means between said spark gap means and said capacitor means and made of material having a very high initial permeability but being magnetically saturable by comparatively low induction, so that upon application of said igniting impulse the inductive reactance of said circuit means between the charged storage capacitor means and the spark gap means is very high and the spark-over between the electrodes is produced by said impulse, while the following discharge of the storage capacitor means across the spark gap means causes a strong current flow inducting immediately full magnetic saturation of said reactance means whereby the initial permeability thereof is practically entirely eliminated.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a schematic diagram illustrating one embodiment of the invention;

FIG. 1a is adiagram illustrating the shape of an impulse appearing in the operation of the arrangement according to the invention;

FIG. lb is a schematic circuit diagram illustrating a modification of the arrangement according to FIG. 1;

FIG. 2 is a diagrammatic illustration, partly in section, of a portion of the arrangement according to FIG. 1;

FIG. 2a illustrates at a larger scale in perspective view a certain detail of a modified embodiment of the invention; and

FIG. 3 is a diagrammatic illustration of a modification of a portion of the arrangement according to FIG. .2.

One embodiment of the invention is illustrated by FIG. 1. The portion to the right of the vertical dividing line marked A is the actual spark gap arrangement and comprises two spark electrodes 1 separated by the spark gap 2 and preferably surrounded by a cylinder or other enclosure 3, a source of electric energy or charge generator 6 connected by lines 4 with the spark electrodes 1, a storage capacitor 5 being connected in parallel with the spark electrodes 1. Thus, the purpose of the arrangement is to charge the storage capacitor 5 to a predetermined potential and to discharge this capacitor across the spark gap 2 by means of the lines or conductors 4 which have at least a portion which has a very low inductance so that a spark will be generated between the electrodes 1 which has a comparatively high current.

In order to achieve this without the aid of auxiliary igniting electrodes at least a portion of the lines or circuit means 4 is surrounded by annular members 7, or, as will be illustrated and described further below by a cylindric member, both these members constituting inductive reactance means and consisting of ferrite material having an extremely high initial permeability and being magnetically saturable by comparatively low induction. Nowadays ferrite material is available Which has an initial permeability ranging between 2,000 and 10,000. Instead of using ferrite cylinders also thin sheet metal of high permeability may be wrapped around the respective portion of the conductors 4. If such inductive reactance means like e.g. the rings 7 are mounted on the circuit means 4 the inductivity of the system is very much increased. For instance, the inductivity of the conductor 4 alone may amount to .1 #11, but by the addition of the surrounding high-permeability material the inductivity is increased to about 50 ,uh.

In order to facilitate the desired spark discharge across the spark gap 2 a steeply rising voltage impulse is 'applied to the spark electrodes 1 in the manner described.

further below from the spark discharge initiator means shown in FIG. 1 to the left of the dividing line marked A. As a result of the very high permeability of the ferrite members or the like surrounding the leads 4 this voltage impulse encounters a very high inductive reactance in the circuit means connecting the storage capacitor 5 with the spark electrodes 1 so that the entire energy of this voltage impulse acts to cause an initiating spark-over between the electrodes 1. Hereby sufficient conductivity is established in the medium or area present between the electrodes 1 for causing without any delay a vigorous discharge of the storage capacitor 5 across the spark gap 2. The resulting discharge current increases to several hundred amperes within an extremely brief time interval amounting e.g. to only .1 ,usec. and produces consequently so strong a magnetic field surrounding the lead or conductor 4 that the ferrite or other members surrounding the latter are immediately completely saturated magnetically with the result that their permeability is reduced to 1. Consequently, they can no longer have any efiect on the inductivity of the main discharge circuit. Consequently the remainder of the discharge of the storage capacitor 5 takes place without encountering inductive reactance and the resulting flow of current is the same as if only the conductors 4 were present without the surrounding inductive reactance means like the ferrite rings 7.

As mentioned above, to the left of the dividing line marked A in FIG. 1 an exmple of spark discharge initiator means is illustrated which comprises the following arrangement for generating the above-mentioned voltage impulse. A primary capacitor 11 is connected with an auxiliary voltage source and in circuit with the primary winding 13a of a small impulse transformer 13b, a normally open switch 12 being provided for causing when moved to closed position a discharge of the capacitor 11 across the Winding 13a. It is to be understood that the switch 12 may consist of any suitable type of switch means including a spark gap, a thyratron or any other suitable electron tube. The secondary winding 13c of the transformer 13b is connected in circuit with a triggering capacitor 14. One terminal of the capacitor 14 is connected across an auxiliary spark gap device 16 and an additional capacitor 15 with one of the spark electrodes 1 while the other terminal of the capacitor 14 is connected with ground and with the other spark electrode 1. In addition, a junction point between the spark gap device 16 and the capacitor 15 is connected via a resistor 17 with the grounded portion of the circuit.

It can be seen from the diagram of FIG. 1 that before the generation and release of the voltage impulse by discharge of the primary capacitor 11 the same potential is present at the capacitor 15 which originally is present at the spark gap electrodes 1 and that both electrodes of the auxiliary spark gap device 16 carry ground potential. However, immediately before initiating the main spark discharge as a result of a discharge of the capacitor 11 the potential at the triggering capacitor 14 rises up to a value which equals the breakdown or igniting voltage of the auxiliary spark gap device 16. The moment a spark-over occurs in this spark gap device 16 the two capacitors 14 and 15 are connected in series across the auxiliary spark gap device 16 so that at the main spark gap electrodes 1 a steep voltage impulse appears the amplitude of which is the sum of the potentials at the capacitors 14 and, 15. The primary spark-over resulting from this voltage impulse results, as stated above, in a spontaneous and reliable discharge of the storage capacitor 5 across the gap 2 between the main spark electrodes 1.

It should be noted that it is advantageous to provide the auxiliary spark gap device 16 with an insulating cylinder 16' closely surrounding the electrodes of this spark device because this causes a particularly steep rise of the spark voltage in the device 16. Moreover, the spark gap device 16 may also'be filled in a well known manner with a non-oxidizing gas e.g. nitrogen so that the device will have a long life without the possibility of oxidation of the electrodes.

FIG. 1a is a diagram in which the ordinates represent values of the discharge current I while the abscissae represent the time t'. The dotted curve is the shape of the current pulse as it would be if the conductor or conductors 4 were not surrounded by ferrite or analogous material. By using ferrite or analogous members in accordance with the invention the shape of the current impulse changes to that which is illustrated 'by the fully drawn curve. One can see that during a brief starting time t the increase of the current is somewhat delayed up to the point P. From there on the shape of the curve is the same as that which is shown in dotted lines for the case where no ferrite or analogous members are used. Depending upon the discharge circuit system that time t amounts to about 5-10 nanoseconds as has been found experimentally. This delay is in most cases negligibly small. However, if it is desired or necessary this small delay can be eliminated in a well known manner by introducing into the circuit arrangement suitable time correcting members so that e.g. the maximum or peak of the current curve is located there where it would be located if no ferrite or analogous members were used. For instance, the inherent delay time of the circuit arrangement could be made particularly small so that a sort of advance time is obtained.

Of course, it is possible to use other impulse generator means than those which are shown at the left of the dividing line marked A in FIG. 1, for instance a well known voltage multiplier circuit as proposed by Marx (see Frank Frungel, Impulstechnik, published Leipzig, Germany, 1960, pages -131).

FIG. 1b illustrates a modification of the apparatus according to the invention which differs from that of FIG. 1 mainly by utilizing for the impulse generator or spark discharge initiator means the above mentioned circuit according to Marx. In this case the voltage supplied by the charge generator 6 and applied to the electrodes 1 serves also to charge a plurality of auxiliary capacitors 9a to 92 via a corresponding number of auxiliary resistors 8a to 8i. Of course the resistors 8a to 8i could be replaced by choke coils. All the capacitors 9a to 9e can be connected in series with each other by producing spark-over across the auxiliary spark gap devices 16a to 16d in the arrangement as illustrated. Such spark-overs can be produced by actuation of a switching device 12a which in the illustrated example is an electron tube. If according to the illustration a thyratron or other electron tube is used as a switching device then the spark-over in the entire spark discharge arrangement can be initiated in a well known manner practically without any inertia with an accuracy within a few nanoseconds. Consequently the spark discharge arrangement is ignited in this case without utilizing a separate voltage source for initiating the discharge. A circuit arrangement as that illustrated by FIG. 1b avoids the use of the comparatively slow acting impulse transformer. In the case of using a thyratron or other electron tube as switching device 12a the control thereof is carried out in a well known manner by means of a grid leak resistor 12b and a coupling capacitor 12c and an input capacitor 12e with a leak resistor 1201. The activating grid voltage is applied at B. The cathode potential for the tube 12a is furnished from the charge generator 6, the charging resistor 12g and the filter capacitor 12 keeping the cathode of the tube 12a at a constant potential.

FIG. 2 illustrates diagrammatically the application of the present invention to a spark gap arrangement which is not permanently assembled as a unit 'but is assembled from a plurality of components which can be separated if desired or necessary. The main spark electrodes 1 are carried by corresponding support members 1a, 1a, respectively, which are conductive and are, in turn, supported by conductive carrier plates 1c and 1d, respectively. However, aninsulator 1b is interposed between the support member 1a and the carrier plate 1d. The spark electrodes 1 are surrounded and enclosed by a transparent cylinder 3 which is mounted between the carrier plates and 1d with the interposition of silicone rubber rings 3b. Screw bolts 3a serve to force the carrier plates 10 and 1d toward each other thus tightly closing the enclosure surrounding the spark electrodes. This spark arrangement is supplied with discharge energy from the storage capacitor 5 via lines 4 connected to the plate 1d and to the support member 1a, respectively, as shown. The capacitor 5 is charged by the charge generator 6 in the same manner as described further above. The conductors 4 and the bolts 3a which serve also as discharge current conductors are surrounded in accordance with the invention either by ferrite rings 7a or 7b or by a cylindrical ferrite member 7c, or finally by high-permeability sheet metal wrapped around conductor 4 as indicated at 70'. Of course, the ferrite members 7a, 7b or 70 need not be circular in contour but may quite as well have any other contour. Also, in certain cases it may be desirable to provide rings or cylinders of ferrite material with radially extending slots 7" as shown in FIG. 1.

However, it has been found to be of particular advantage to use a plurality of individual rings as shown at 7a or 7b. But since a voltage pulse develops along the high inductance means constituted by these rings which might lead to a spark-over between the ferrite members having some conductivity, it is recommended to separate these individual rings e.g. the rings 712 from each other and from the central conductor 4 by insulating material as indicated at 7e and 7e. The discs 7e are also annular members and preferably have an outer diameter somewhat larger than the outer diameter of the ferrite rings 7b. The ignition of the spark gap arrangement according to FIG. 2 is to be produced in the manner described further above by suitable spark discharge initiator means which are supposed to be provided at the right of the separating line A in the same manner as indicated at the left of the line marked A in FIGS. 1 and 1b.

As far as the mechanical assembly of the arrangement is concerned it is advantageous to use a plurality of ring members which are pushed over the conductors 4 or 3a. However, in some cases it may be desirable to use an arrangement as illustrated by FIG. 20. Here a conductor 4 is coiled around a ferrite ring 7' in such a manner that the ring passes through consecutive convolutions 4" of the conductor. In this manner as many convolutions may be used per ring as space would permit. Also in this case the inductive reactance drops as a result of magnetic saturation of the ring material by the main spark discharge, the drop corresponding to the value of the initial permeability.

It has been found that it is of particular advantage to arrange the ferrite rings 7 surrounding a conductor 4 together with the storage capacitors 5 within a common housing 18 which is usually provided for surrounding the storage capacitors. This arrangement is diagrammatically illustrated by FIG. 3.

The arrangement according to the invention will be found to be of particular value and usefulness in connection with photographic flash lamps as well as in connection with spark light apparatus used for the purpose of measuring the altitude of clouds, for measuring the range of visibility or for giving fog warning signals. The same applies to all other photographic or signaling devices which utilize light impulses. The arrangement may also be used advantageously for igniting spark gaps in devices utilizing the so-called pinch effect in such discharges because in these cases always the problem exists how to assure an extremely precise timing of the ignition in connection with as simple as possible an electrode construction. Since the arrangement according to the invention permits the use of a high repetition frequency it can also be used in electric control devices which utilize spark gaps with or without elevated pressure in the areas of the spark gap as switching devices.

It will be understood that each of the elements described above or two or more together, may also find a useful application in other types of spark discharge arrangements differing from the types described above.

While the invention has been illustrated and described as embodied in spark discharge arrangement with only two spark gap electrodes without auxiliary or igniting electrodes, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the specific or generic aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed and desired to be secured by Letters Patent is:

1. Spark discharge arrangement, comprising, in combination, spark gap means having two spaced spark electrodes; a source of electric energy; circuit means having at least a coilless portion of low inductance and connecting said spark gap means with said source of elecric energy, the low inductance portion of said circuit means being adapted to conduct high currents; storage capacitor means included in said circuit means and connected in parallel with said spark gap means, said storage capacitor means being chargeable by said source to a predetermined potential and dischargeable across said spark gap means when a sufiicient predetermined conductivity is established between said two electrodes, the discharge from said storage capacitor means occurring directly through said coilless portion of low inductance and across said spark gapmeans; spark discharge initiator means associated with said circuit means and connected in parallel with said storage capacitor means and said spark gap means, said spark discharge initiator means being directly connected to the electrodes of said spark gap means and capable of applying to said spark gap means a steeply rising igniting impulse causing a spark-over between said electrodes so as to produce thereby said predetermined conductivity therebetween; and inductive reactance means unconnected to said circuit means and only externally surrounding at least a portion of said low inductance portion of said circuit means between said spark gap means and said capacitor means, said inductive reactance means comprising a plurality of hollow substantially annular members made of ferrite-like material and having a very high initial permeability but being magnetically saturable by comparatively low induction, so that upon application of said igniting impulse the inductive reactance of said circuit means between the charged storage capacitor means and the spark gap means is very high and the spark-over between the electrodes is produced by said impulse, while the following discharge of the storage capacitor means across the spark gap means causes a strong current flow inducing immediately full magnetic saturation of said reactance means whereby the initial permeability thereof is practically entirely eliminated.

2. An arrangement as claimed in claim 1, including insulation between said annular members and between the latter and said portion of said circuit means surrounded thereby.

3. An arrangement as claimed in claim 1, wherein said spark gap means comprise a spark chamber including structural members serving also as conductors, said structural members constituting said portion of said circuit means surrounded by said inductive reactance means.

4. An arrangement as claimed in claim 1, wherein said storage capacitor means include at least one capacitor and a housing surrounding the latter, said. portion of said circuit means surrounded by said inductive reactance means being arranged also in said housing.

5. An arrangement as claimed in claim 1, wherein said spark discharge initiator means comprise at least one triggering capacitor, auxiliary, impulse generator means for briefly charging said triggering capacitor by application of an impulse thereto, and atleast one auxiliary spark gap device in circuit with said triggering capacitor and said two electrodes of said spark gap means so that in response to an impulse applied to said triggering capacitor a first spark-over is caused in said auxiliary spark gap device resulting in an igniting impulse acting on said spark gap means.

6. An arrangement as claimed in claim 5, wherein said impulse generator means include an auxiliary voltage source, a primary capacitor chargeable by said voltage source, and impulse transformer means having a primary winding and a normally open switch means in circuit with said primary capacitor for having the latter discharged across said primary winding when said switch means is closed, and a secondary winding in circuit with said triggering capacitor.

7. An arrangement as claimed in claim 6, wherein an additional capacitor is connected between one electrode of said auxiliary spark gap device and one electrode of said spark gap means, while .a high resistance means is connected between the other electrode of said auxiliary spark gap device and the other electrode of said Spark gap means so that upon release of the triggering impulse and the resulting spark-over at the auxiliary spark gap device the voltage of the ensuing igniting impulse is superimposed on the reference voltage existing between said two electrodes of the spark gap means due to their connection with said source of electric energy.

8. An arrangement as claimed in claim 5, wherein said spark discharge initiator means comprise a plurality of triggering capacitors and a plurality of auxiliary spark gap devices in circuit with said triggering capacitors, respectively, in a cascade arrangement and with said two electrodes of said spark gap means, said triggering capacitors being connected for being chargeable by said source of electric energy.

9. Spark discharge arrangement, comprising, in combination, spark gap means having two spaced spark electrodes; a source of electric energy; circuit means having at least a coilless portion of low inductance and connecting said spark gap means with said source of electric energy, the low inductance portion of said circuit means being adapted to conduct high currents; storage capacitor means included in said circuit means and connected in parallel with said spark gap means, said storage capacitor means being chargeable by said source to a predetermined potential and dischargeable across said spark gap means when a sutficient predetermined conductivity is established between said two electrodes, the discharge from said storage capacitor means occurring directly through said coilless portion of low inductance and across said spark gap means; spark discharge initiator means associated with said circuit means and connected in par-allel with said storage capacitor means and said spark gap means, said spark discharge initiator means being directly connected to the electrodes of said spark gap means and capable of applying to said spark gap means a steeply rising igniting impulse causing a spark-over between said electrodes so as to produce thereby said predetermined conductivity therebetween; and inductive reactance means unconnected to said circuit means and only externally surrounding at least a portion of said low inductance portion of said circuit means between said spark gap means and said capacitor means, said inductive reactance means comprising a plurality of hollow substantially annular members made of ferrite-like material, being split in radial direction having a very high initial. permeability but being magnetically saturable by comparatively low induction, so that upon application of said igniting impulse the inductive reactance of said circuit means between the charged storage capacitor means and the spark gap means is very high and the spark-over between the electrodes is produced by said impulse, while the following discharge of the storage capacitor means across the spark gap means causes a strong current flow inducing immediately full magnetic saturation of said reactance means whereby the initial permeability thereof is practically entirely eliminated.

, 10. Spark discharge arrangement, comprising, in combination, spark gap means having two spaced spark electrodes; a source of electric energy; circuit means having at least a coilless portion of low inductance and connecting said spark gap means with said source of electric energy, the loW inductance portion of said circuit means being adapted to conduct high currents; storage capacitor means included in said circuit means and connected in parallel with said spark gap means, said storage capacitor means being chargeable by said soure to a predetermined potential and dischargeable across said spark gap means when a suflicient predetermined conductivity is established between said two electrodes, the discharge from said storage capacitor means occurring directly through said coilless portion of low inductance and across said spark gap means; spark discharge initiator means associated with said circuit means and connected in parallel with said storage capacitor means and said spark gap means, said spark discharge initiator means being directly connected to the electrodes of said spark gap means and capable of applying to said spark gap means a steeply rising igniting impulse causing a sparkover between said electrodes so as to produce thereby said predetermined conductivity therebetween; and inductive reactance means unconnected to said circuit means and only externally surrounding at least a portion of said low inductance portion of said circuit means between said spark gap means and said capacitor means, said inductive reactance means comprising at least one hollow cylindrical member made of ferrite-like material and having a very high initial permeability but being magnetically saturable by comparatively low induction, so that upon application of said igniting impulse the inductive reactance of said circuit means between the charged storage capacitor means and the spark gap means is very high and the spark-over between the electrodes is produced by said impulse, while the following discharge of the storage capacitor means across the spark gap means causes a strong curent flow inducing immediately full magnetic saturation of said reactance means whereby the initial permeability thereof is practically entirely eliminated.

11. Spark discharge arrangement, comprising, in combination, spark gap means having two spaced spark electrodes; a source of electric energy; circuit means having at least a coilless portion of low inductance and conmeeting said spark gap means with said source of electric energy, the low inductance portion of said circuit means being adapted to conduct high currents; storage capacitor means included in said circuit means and connected in parallel with said spark gap means, said storage capacitor means :being chargeable by said source to a predetermined potential and dischargeable across said spark gap means when a sufiicient predetermined conductivity is established between said two electrodes, the discharge from said storage capacitor means occurring directly through said coilless portion of low inductance and across said spark gap means; spark discharge initiator means associated with said circuit means and connected in parallel 'with said storage capacitor means and said spark gap means, said spark discharge initiator means being directly connected to the electrodes of said spark gap means and capable of applying to said spark gap means a steeply rising igniting impulse causing a spark-over between said electrodes so as to produce thereby said predetermined conductivity therebetween; and inductive reactance means unconnected to said circuit means and only externally surrounding at least a portion of said low inductance portion of said circuit means between said spark gap means and said capacitor means and made of thin sheet material wound about said portion of said circuit means and having a very high initial permeability but being magnetically saturable by comparatively low induction, so that upon application of said igniting impulse the inductive reactance of said circuit means between the charged storage capacitor means and the spark gap means is very high and the spark-over between the electrodes is produced by said impulse, While the following discharge of the storage capacitor means across the spark gap means causes a strong current flow inducing immediately full magnetic saturation of said reactance means whereby the initial permeability thereof is practically entirely eliminated.

References Cited by the Examiner UNITED STATES PATENTS 2,594,890 4/1952 Ellwood 336- 2,737,612 3/1956 Sims 315289 X 2,880,375 3/1959 Cresswell 315176 X 2,930,920 3/1960 Bird 3 l3161 2,951,971 9/1960 Schultz 315--176 X JOHN W. HUCKERT, Primary Examiner.

D. O. KRAFT, Assistant Examiner. 

1. SPARK DISCHARGE ARRANGEMENT, COMPRISING, IN COMBINATION, SPARK GAP MEANS HAVING TWO SPACED SPARK ELECTRODES; A SOURCE OF ELECTRIC ENERGY; CIRCUIT MEANS HAVING AT LEAST A COILLESS PORTION OF LOW INDUCTANCE AND CONNECTING SAID SPARK GAP MEANS WITH SAID SOURCE OF ELECTRIC ENERGY, THE LOW INDUCTANCE PORTION OF SAID CIRCUIT MEANS BEING ADAPTED TO CONDUCT HIGH CURRENTS; STORAGE CAPACITOR MEANS INCLUDED IN SAID CIRCUIT MEANS AND CONNECTED IN PARALLEL WITH SAID SPARK GAP MEANS, SAID STORAGE CAPACITOR MEANS BEING CHARGEABLE BY SAID SOURCE TO A PREDETERMINED POTENTIAL AND DISCHARGEABLE ACROSS SAID SPARK GAP MEANS WHEN A SUFFICIENT PREDETERMINED CONDUCTIVITY IS ESTABLISHED BETWEEN SAID TWO ELECTRODES, THE DISCHARGE FROM SAID STORAGE CAPACITOR MEANS OCCURRING DIRECTLY THROUGH SAID COILLESS PORTION OF LOW INDUCTANCE AND ACROSS SAID SPARK GAP MEANS; SPARK DISCHARGE INITIATOR MEANS ASSOCIATED WITH SAID CIRCUIT MEANS AND CONNECTED IN PARALLEL WITH SAID STORAGE CAPACITOR MEANS AND SAID SPARK GAP MEANS, SAID SPARK DISCHARGE INITIATOR MEANS BEING DIRECTLY CONNECTED TO THE ELECTRODES OF SAID SPARK GAP MEANS AND CAPABLE OF APPLYING TO SAID SPARK GAP MEANS A STEEPLY RISING IGNITING IMPULSE CAUSING A SPARK-OVER BETWEEN SAID ELECTRODES SO AS TO PRODUCE THEREBY SAID PREDETERMINED CONDUCTIVITY THEREBETWEEN; AND INDUCTIVE REACTANCE MEANS UNCONNECTED TO SAID CIRCUIT MEANS AND ONLY EXTERNALLY SURROUNDING AT LEAST A PORTION OF SAID LOW INDUCTANCE PORTION OF SAID CIRCUIT MEANS BETWEEN SAID SPARK GAP MEANS AND SAID CAPACITOR MEANS, SAID INDUCTIVE REACTANCE MEANS COMPRISING A PLURALITY OF HOLLOW SUBSTANTIALLY ANNULAR MEMBERS MADE OF FERRITE-LIKE MATERIAL AND HAVING A VERY HIGH INITIAL PERMEABILITY BUT BEING MAGNETICALLY SATURABLE BY COMPARATIVELY LOW INDUCTION, SO THAT UPON APPLICATION OF SAID IGNITING IMPULSE THE INDUCTIVE REACTANCE OF SAID CIRCUIT MEANS BETWEEN THE CHARGED STORAGE CAPACITOR MEANS AND THE SPARK GAP MEANS IS VERY HIGH AND THE SPARK-OVER BETWEEN THE ELECTRODES IS PRODUCED BY SAID IMPULSE, WHILE THE FOLLOWING DISCHARGE OF THE STORAGE CAPACITOR MEANS ACROSS THE SPARK GAP MEANS CAUSES A STRONG CURRENT FLOW INDUCING IMMEDIATELY FULL MAGNETIC SATURATION OF SAID REACTANCE MEANS WHEREBY THE INITIAL PERMEABILITY THEREOF IS PRACTICALLY ENTIRELY ELIMINATED. 